Spindle motor for hard disks with cup-shaped sleeve

ABSTRACT

This invention relates to a driving device, especially for hard disk drives, consisting of a stator, a rotor, an axis as well as corresponding bearings. The winding packet constituting the drive is arranged, together with the corresponding laminated core, on a holding sleeve, which projects axially on both sides over the laminated core. Possible production methods relating to this invention are also described.

FIELD OF THE INVENTION

The present invention is directed to a drive device, especially for harddisk drives, as well as the corresponding production methods.

BACKGROUND OF THE INVENTION

According to the present state of technology, the spindle motor has arotor in the form of an external rotor motor; the stator is positionedby means of a projection that gradually protrudes from the casing,equally radial to the swiveling axis and axial to the height. Thisprojection, which has an axial step, is an integrated component of thecasing (flange, baseplate).

The document U.S. Pat. No. 5,343,104 makes a fan motor known that has anexternal rotor motor, which has a rotating axis. On this motor a flangeis arranged between the armature and rotor. The flange serves, on theone hand, as a receptacle for individual parts, and on the other hand,serves as a mechanical divider between the windings of the windingpacket and represents the rotating axis and the receptacle flange in themotor's cover.

The document WO 90 13167 in comparison concerns a stabilized spindlemotor for hard disk drive with a fixed axis, which has two support ringsto stabilize the armature (rotor) and to pre-emphasize the oscillationfrequency in a high frequency area and, therefore, result in a connectedreduction of its oscillation amplitude. Both of these support rings arearranged in radial inner and outer areas under the armature (rotor). Theinner support ring is designed so that in the assembled state it islocated inside the central opening of the armature (rotor) and resultsin its radial positioning. The axial positioning of the armature (rotor)follows by means of the outer support ring. There are also two supportrings for the winding packet, which, in addition to positioning thearmature (rotor), pre-emphasize the armature's (rotor's) oscillation.

The disadvantage of this known solution is that the constantly narrowingroom with the simultaneous higher space factor of the winding packetincreases the danger of jammed windings between the winding packet andthe stator's projection. Since deficiently installed winding packetscannot be detected by simple visual checks or can only be discoveredconditionally by electrical evaluation, there is, at the same time, anincreased risk that the faulty product will be delivered and its defectswill be detected only during its actual use. Simultaneously, the portionof rejections increases, which is business-wise and economically notsound.

Another disadvantage is that the winding, that points radially inward onthe air gap between the rotor and stator, bridges over the air gap andcomes into contact with the rotor's surface, thereby, damaging it.

There are already winding packets that are plastic-extrusion coated orplaced on a plastic holder. These solutions remove the above-describeddisadvantages, but are in many cases not possible to use because ofrestricted space.

The task, therefore, is to improve the winding packet's holder at thestator of a driving device for a hard disk storage (the type asdescribed at the beginning), so that in all cases of restricted space,as described, the disadvantages of this state of technology can beprevented.

SUMMARY OF THE INVENTION

A fundamental characteristic of the invention is the invention-relateddrive device that has a holding sleeve with axial, sleeve-shapedprojection, as well as horizontal radial-formed projections, which arearranged so that the winding packet in the transition is centeredbetween an axial and a horizontal radial projection and that the holdingsleeve projects axially on both sides over the laminated core.

The function of the integrated step-by-step projection is taken over bya separate cup- or pipe-shaped holder, which projects axially over thelaminated core and is positioned radially and axially by means of astep-shaped designed projection in the casing.

The laminated core is then fastened securely to the pipe- or cup-shapedadditional component by compression, adhesion or other means offastening and then is first spooled.

This measure prevents the winding from becoming stripped and jammedduring the stator's assembly in the casing. At the same time, thecylindrical restriction surfaces of the pipe- or cup-shaped holders thatproject out both sides over the winding packet, protect (it) fromcontact between the rotating hub of the rotor and loose windings of thestator.

It is hereby preferred that the holding sleeve projects at leastone-sided over the winding packet. This offers a further advantage thatan unintentional damaging of the winding packet can be prevented duringthe fastening at a corresponding component of the driving device.According to the designed embodiment, both sides can also project out.

The holding sleeve can be equipped with an offset bend. This bend caneither serve as a stop for the laminated core or can secure and adjustthe positioning in relation to the stator and/or the rotor. Of course,it is possible to install two such bends.

The holding sleeve is centered opposite the stator and/or the rotor,and, if necessary, the axis. This can either take place by the alreadydescribed bend, which is placed on a projection in the stator and/orrotor. Of course, the sleeve can also be equipped with a projection, anextension or flange that is supported directly on the axis. In this lastdescribed embodiment, it is possible then that the stator, the rotor andthe holding sleeve, together with the laminated core and windingpackets, all center opposite the axis together. Thus, the assemblyprecision is increased.

Of course, it is also possible to center the holding sleeve aloneopposite the stator or rotor.

The holding sleeve, can, for example, have a self-sticking adhesivecoating for fastening.

To further increase the precision, the bearings used can be pre-stressedagainst each other clearance-free.

The production methods provide first that the holding sleeve is equippedwith a laminated core and is installed so that the holding sleeveprotrudes on both sides. Only afterwards does a winding of the laminatedcore take place. Then the holding sleeve, together with the laminatedcore and winding packet, are inserted.

Although, in the accompanying figures, the fastening and centering ofthe holding sleeves, laminated core and winding packets on the statorare represented, a fastening and centering of these elements on therotor's axis is, of course, also possible.

Altogether, an essential improvement emerges that indicates therejection quotas are decreased and the assembly precision is increased.

The holding sleeve also serves as a radial, inwardly directed protectioncap against the (rotating) air gap and prevents the windings of thewinding packet from bridging over the air gap and damaging the rotatingsurfaces of the rotor.

Furthermore, this protection cap prevents undesirable vibrations fromthe winding packet.

The invention-related objectives of the submitted present inventionresult not only from the matter of the particulars in the patent claims,but also the various combinations of the individual patent claims.

All records, documents and evidence, inclusive of the abstract, open anddisclosed statements and declarations and indications and features,especially those represented embodiments in the drawings, will beclaimed as fundamental and significant to the invention as far as theclaims individually or in combinations are relative to the position thatthe technology is new.

The invention at hand will be explained more precisely by the variousembodiments shown by the representational drawings. Hereby, additionalsignificant features and advantages of the invention will be concludedfrom the drawings and their descriptions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: A half section through a layout of a spindle motor in a firstembodiment;

FIG. 2: A half section through a second embodiment of the same spindlemotor.

The spindle motor, according to FIGS. 1 and 2, consists of a centralaxis (1) on which the bearings (13) are flanged in reciprocal distancefrom one another.

The bearings (13) carry the rotor (4), which is profiled as somewhatbell-shaped and carries an upper sealing ring (3), which seals thebearings (13) outside.

DETAILED DESCRIPTION

The stator supports a winding packet (5), which consists of a laminatedcore (6) and the winding (21) placed on it.

It is now important that the winding packet (5) is centered with thelaminated core (6) on the holding sleeve (7). For this purpose thisforms an upper axial projection (8), which becomes a short, horizontaland bent projection (8 a), which changes on its side again into an axialprojection (8 b). In this way the radial inner-lying front of thelaminated core (6) is placed centrally in the transition between theprojection (8) and (8 a) and fastened there. The fastening results fromeither adhesion or compression or by adhesion without compression or byboth fastening procedures.

The axial projection (8 b) goes, however, with a 90° angle into ahorizontal flange (9) that is centered with a front (12) on the axis(1).

This centering on the axis is not absolutely necessary, but can takeplace on a flange-sided projection (20).

The fastening of the holding sleeve (7) on the stator takes place whenthe underside of the flange (9) has an adhesive coating (10); which, forexample, can be a double adhesive tape made of an applied adhesivecoating or made from another fastening means. A better, more secure,holding can be attained when this adhesive coating (10) is applied in adeepened groove (11) in the stator (2).

This way space is saved because the inside edge of the flange (9) isthen somewhat flush with the inside edge (22) of the stator (2).

The special production steps in reference to the invention are alsoimportant because the entire winding packet (5) with the laminated core(6) and the winding (21) is produced together with the holding sleeve(7). Then this complete system is first placed in the motor that isrepresented by FIGS. 1 and 2.

Besides, the motor consists in a known manner of a permanent magneticring (14) that is surrounded on its radial outer-lying perimeter by aback close ring (15).

The back close ring (15) is pressed into the rotor (4), where itadheres.

FIG. 2 shows another embodiment of the invention, where it isrecognizable that the horizontal flange (9) in accordance with FIG. 1can also be left out, and instead, two axial flanges, which are placedco-axially to one another or concentrically, can be used. There, tworepresented holding sleeves (16) consist of an upper, axial flange (17),which is separated by a short horizontal shoulder (18) from the loweraxial flange (19), resulting in the fastening of the holding sleeve (16)on the stator (2), which, again, has in the horizontal shoulder's (18)area, an adhesive surface on which the holding sleeve (16) is fastenedon the projection (20) of the stator (2).

Similarly, the adhesion may also take place only in the area of thevertical flange (19) on the projection (20) of the stator (2), and,likewise, the adhesion may occur on the shoulder (18) or also on theshoulder (19) with the stator (2).

In FIG. 1 it can also be provided that the horizontal flange (9) is leftout and that instead, the vertical part of the holding sleeve (7) isdirectly anchored with its lower front in a corresponding ring groove ofthe stator.

What is claimed is:
 1. A driving device suitable for use in hard diskdrives, the driving device comprising: a stator comprising a deepenedgroove, wherein the deepened groove is aligned perpendicular to a fixedaxis of the stator; a rotor positioned pivotable on the fixed axis ofthe stator on corresponding bearings; a winding packet comprising alaminated core and a corresponding winding fastened on the stator, thelaminated core having a radially inwardly directed front side separatedfrom the rotor by an air gap between the rotor and the stator, theradially inwardly directed front side of the laminated core beingdirected towards a surface of the rotor; and a holding sleeve disposedpartially within the elongate groove of the stator which is formed as aseparate component from the stator and which is positioned in the airgap, the holding sleeve concave radially outward from the fixed axis ofthe stator along the fixed axis of the stator, wherein the holdingsleeve has an axial projection and a horizontal radially formedprojection positioned so that the winding packet is centered in atransition between the axial projection and the horizontal radiallyformed projection, the holding sleeve projects beyond the laminatedcore, and wherein a radial inner surface of the stator core is fitted toa radial outer surface of the holding sleeve.
 2. The driving device,according to claim 1, wherein the axial projection of the holding sleeveprojects axially beyond at least one side of the winding packet.
 3. Thedriving device, according to claim 1, wherein the holding sleeve iscentered opposite at least one of the stator and the axis and,respectively, the rotor.
 4. The driving device, according to claim 3,wherein the holding sleeve is centered over a radial flange on the axisand, respectively, the rotor.
 5. The driving device, according to claim1, wherein the holding sleeve comprises an adhesive coating for thepurpose of attachment on the deepened groove of the stator.
 6. Thedriving device, according to claim 1, wherein the corresponding bearingsare pre-stressed, free from play, against each other.
 7. The drivingdevice, according to claim 1, wherein a radial inner surface of a radialinner opening centered in a bottom portion of the holding sleeve isfitted to a radial outer surface of the fixed axis of the stator.
 8. Thedriving device, according to claim 1, wherein the stator core is fittedto a radial outer surface of a top portion of the holding sleeve, and aninner surface of a bottom portion of the holding sleeve is fitted to aradial outer surface of a projection of the stator.